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Colorado on the 2023 USDA hardiness map

Colorado Planting Zones by City and ZIP Code

Colorado runs from zones 4a to 7a; 44% of its ZIPs are 6a, Denver is 6a and Colorado Springs is 6a.

625 ZIP codes

Colorado runs from zones 4a to 7a

The coldest night of the winter averages -30°F to -25°F in the coldest of Colorado’s ZIP codes and 0°F to 5°F in the warmest. Most of the state is zone 6a.

  • 4aunder 1% of ZIPs (2), -30°F to -25°F
  • 4b2% of ZIPs (10), -25°F to -20°F
  • 5a12% of ZIPs (73), -20°F to -15°F
  • 5b35% of ZIPs (217), -15°F to -10°F
  • 6a44% of ZIPs (274), -10°F to -5°F
  • 6b6% of ZIPs (36), -5°F to 0°F
  • 7a2% of ZIPs (13), 0°F to 5°F

Planting zones of Colorado cities

CityZoneColdest night, on averageSince 2012
Denver802026a-10°F to -5°Fhalf a zone warmer than 2012 (5b)
Colorado Springs809036a-10°F to -5°Fhalf a zone warmer than 2012 (5b)
Grand Junction815017a0°F to 5°Fsame as 2012
Fort Collins805215b-15°F to -10°Fsame as 2012
Pueblo810036a-10°F to -5°Fhalf a zone warmer than 2012 (5b)
Leadville804615a-20°F to -15°Fhalf a zone warmer than 2012 (4b)

Tap a ZIP for that address’s frost dates and this month’s jobs.

Your address

Find your zone anywhere in Colorado

A ZIP code or a town gives you its zone, how it moved since 2012, the frost dates at the nearest NOAA station, and the jobs for this month timed from them.

Month by month

What to plant in Colorado this month

The calendar for each of Colorado's main zones, from vegetables to pruning and winter protection, each job tied to the extension page it comes from. Pick a month, or read the whole year below it.

Timed from the median frost dates of the 40 NOAA stations in Colorado’s zone 6a: last spring frost May 4, first fall frost Oct 9. Your own ZIP’s frost dates move every window, so the ZIP tool times them for you.

Pick a month above to see every job in it.

The year at a glance

  1. Start vegetable seeds indoorsJan to Apr
  2. Sow vegetables in the gardenApr to May
  3. Sow the fall vegetable gardenJun to Aug
  4. Set out transplantsApr to May
  5. Plant trees and shrubsMar 23 to May 18 and Sep 25 to Nov 13
  6. Plant garlicSep 25 to Oct 30
  7. Plant tulips and other spring bulbsOct 16 to Oct 23
  8. Divide fall-blooming perennialsApr 13 to May 25
  9. Divide spring and summer-blooming perennialsAug 28 to Oct 9
  10. Prune trees and summer-flowering shrubs while dormantFeb 23 to Apr 6
  11. Prune spring-flowering shrubs after they bloomApr 20 to Jun 15
  12. Water evergreens and new plantings until the ground freezesSep 11 to Nov 20
  13. Mulch perennial crowns once the ground freezesNov 20 to Dec 4
  14. Pull back the winter mulchMar 16 to Mar 30
  15. Put hardware cloth around young tree trunksOct 9 to Nov 20
  16. Dig and store dahlia and gladiolusOct 9 to Oct 16
  17. Cut back perennials after a hard freezeOct 16 to Nov 13
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What changed in Colorado since 2012

Every ZIP on both maps
47%
ZIP codes now warmer
294 of 625 moved up at least half a zone
313
In the same half zone
unchanged since 2012
25
A full zone warmer
moved up two half zones
18
Colder than 2012
moved down at least half a zone

Compared ZIP by ZIP from the 2023 and 2012 USDA tables; 625 Colorado ZIP codes appear in both.

The 2023 map

Why Colorado’s zones moved

Of the cities above, Denver went from 5b to 6a, Colorado Springs went from 5b to 6a, Pueblo went from 5b to 6a and Leadville went from 4b to 5a.

The USDA explains the national picture: “When compared to the 2012 map, the 2023 version reveals that about half of the country shifted to the next warmer half zone, and the other half of the country remained in the same half zone.” The new map uses 1991 to 2020 and more than 13,000 weather stations, so it draws Colorado’s hills, valleys and cities more finely than the 2012 map did.

A warmer zone changes which perennials and shrubs come through the winter, not when the garden gets planted; that still follows the frost dates.

A hand pressing a single garlic clove into loose, freshly tilled brown soil
Garlic goes in around the first fall frost, from about two weeks before it to three weeks after, so the cloves root before the ground freezes. Hardneck types suit a cold winter and softneck types a mild one. “Planting the Garlic” by Dwight Sipler from Stow, MA, USA, CC BY 2.0
Colorado gardening

Frost dates and seed starting in Colorado

Seed starting calendar for ColoradoWhen to start each vegetable indoors, from the frost at your nearest station.First frost in ColoradoWhen the first fall frost usually arrives across Colorado.Frost dates by ZIPYour last spring and first fall frost, with the odds either side.Lawn care calendar for ColoradoWhen to seed, feed and overseed the lawn.When to plant garlicThe fall planting window by ZIP.When to plant tulip bulbsOnce the soil cools, timed to your first frost.
Questions

Colorado planting zone questions

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Other states

Planting zones by state

Maine: zones 3b to 7a, mostly 5aME5aNew Hampshire: zones 4a to 6b, mostly 6aNH6aVermont: zones 4a to 6a, mostly 5aVT5aMassachusetts: zones 5b to 7b, mostly 6bMA6bConnecticut: zones 6a to 7b, mostly 6bCT6bRhode Island: zones 6b to 7b, mostly 7aRI7aNew York: zones 4a to 7b, mostly 6aNY6aNew Jersey: zones 6b to 8a, mostly 7aNJ7aPennsylvania: zones 5b to 8a, mostly 6bPA6bDelaware: zones 7a to 8a, mostly 7bDE7bMaryland: zones 6a to 8a, mostly 7bMD7bVirginia: zones 6a to 8b, mostly 7bVA7bWest Virginia: zones 5b to 7a, mostly 7aWV7aNorth Carolina: zones 6b to 9a, mostly 8aNC8aSouth Carolina: zones 8a to 9b, mostly 8bSC8bGeorgia: zones 7a to 9a, mostly 8aGA8aFlorida: zones 8b to 11b, mostly 10aFL10aAlabama: zones 7b to 9b, mostly 8bAL8bTennessee: zones 6b to 8a, mostly 7bTN7bKentucky: zones 6b to 7b, mostly 7aKY7aOhio: zones 6a to 7a, mostly 6bOH6bIndiana: zones 5b to 7a, mostly 6aIN6aIllinois: zones 5a to 7a, mostly 6aIL6aMichigan: zones 4a to 7a, mostly 6aMI6aWisconsin: zones 3b to 6a, mostly 5bWI5bMinnesota: zones 3a to 5a, mostly 4bMN4bMississippi: zones 7b to 9a, mostly 8bMS8bLouisiana: zones 8b to 10a, mostly 9aLA9aArkansas: zones 7a to 8b, mostly 8aAR8aTexas: zones 6b to 10b, mostly 8bTX8bOklahoma: zones 6b to 8a, mostly 7bOK7bMissouri: zones 5b to 8a, mostly 6bMO6bIowa: zones 4b to 6a, mostly 5aIA5aKansas: zones 6a to 7a, mostly 6bKS6bNebraska: zones 5a to 6a, mostly 5bNE5bSouth Dakota: zones 4a to 5b, mostly 4bSD4bNorth Dakota: zones 3b to 4b, mostly 4aND4aMontana: zones 3b to 6b, mostly 4bMT4bWyoming: zones 4a to 5b, mostly 5aWY5aColorado: zones 4a to 7a, mostly 6aCO6aNew Mexico: zones 5a to 8b, mostly 7bNM7bWashington: zones 6a to 9b, mostly 8bWA8bOregon: zones 5b to 9b, mostly 8bOR8bCalifornia: zones 5b to 11a, mostly 9bCA9bIdaho: zones 4a to 7b, mostly 6bID6bUtah: zones 4a to 8b, mostly 6aUT6aNevada: zones 5a to 10a, mostly 9bNV9bArizona: zones 5b to 10a, mostly 9bAZ9bAlaska: zones 1a to 8b, mostly 5aAK5aHawaii: zones 10b to 13a, mostly 12bHI12b
Each state is colored by the zone most of its ZIP codes are in; the state page has the full range. Tap a state.

Sources. USDA Plant Hardiness Zone Map, ZIP code tables (2023 and 2012), PRISM Climate Group, Oregon State University; USDA Plant Hardiness Zone Map; USDA Unveils Updated Plant Hardiness Zone Map (USDA Agricultural Research Service, November 15, 2023); NOAA NCEI U.S. Climate Normals 1991-2020, annual/seasonal, by station (v1.0.1); NC State Extension Gardener Plant Toolbox. Zones are read from the PRISM ZIP code tables, read Oct 9, 2026; a ZIP code’s zone is the zone at its center. The calendar’s extension sources are listed on the planting zones page and under each job.